<?php
/**
 * CodeIgniter
 *
 * An open source application development framework for PHP
 *
 * This content is released under the MIT License (MIT)
 *
 * Copyright (c) 2014 - 2016, British Columbia Institute of Technology
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 *
 * @package    CodeIgniter
 * @author    EllisLab Dev Team
 * @copyright    Copyright (c) 2008 - 2014, EllisLab, Inc. (https://ellislab.com/)
 * @copyright    Copyright (c) 2014 - 2016, British Columbia Institute of Technology (http://bcit.ca/)
 * @license    http://opensource.org/licenses/MIT	MIT License
 * @link    https://codeigniter.com
 * @since    Version 1.3.0
 * @filesource
 */
defined('BASEPATH') OR exit('No direct script access allowed');

/**
 * Postgre Database Adapter Class
 *
 * Note: _DB is an extender class that the app controller
 * creates dynamically based on whether the query builder
 * class is being used or not.
 *
 * @package        CodeIgniter
 * @subpackage    Drivers
 * @category    Database
 * @author        EllisLab Dev Team
 * @link        https://codeigniter.com/user_guide/database/
 */
class CI_DB_postgre_driver extends CI_DB
{

    /**
     * Database driver
     *
     * @var    string
     */
    public $dbdriver = 'postgre';

    /**
     * Database schema
     *
     * @var    string
     */
    public $schema = 'public';

    // --------------------------------------------------------------------

    /**
     * ORDER BY random keyword
     *
     * @var    array
     */
    protected $_random_keyword = array('RANDOM()', 'RANDOM()');

    // --------------------------------------------------------------------

    /**
     * Class constructor
     *
     * Creates a DSN string to be used for db_connect() and db_pconnect()
     *
     * @param    array $params
     * @return    void
     */
    public function __construct($params)
    {
        parent::__construct($params);

        if (!empty($this->dsn)) {
            return;
        }

        $this->dsn === '' OR $this->dsn = '';

        if (strpos($this->hostname, '/') !== FALSE) {
            // If UNIX sockets are used, we shouldn't set a port
            $this->port = '';
        }

        $this->hostname === '' OR $this->dsn = 'host=' . $this->hostname . ' ';

        if (!empty($this->port) && ctype_digit($this->port)) {
            $this->dsn .= 'port=' . $this->port . ' ';
        }

        if ($this->username !== '') {
            $this->dsn .= 'user=' . $this->username . ' ';

            /* An empty password is valid!
             *
             * $db['password'] = NULL must be done in order to ignore it.
             */
            $this->password === NULL OR $this->dsn .= "password='" . $this->password . "' ";
        }

        $this->database === '' OR $this->dsn .= 'dbname=' . $this->database . ' ';

        /* We don't have these options as elements in our standard configuration
         * array, but they might be set by parse_url() if the configuration was
         * provided via string. Example:
         *
         * postgre://username:password@localhost:5432/database?connect_timeout=5&sslmode=1
         */
        foreach (array('connect_timeout', 'options', 'sslmode', 'service') as $key) {
            if (isset($this->$key) && is_string($this->key) && $this->key !== '') {
                $this->dsn .= $key . "='" . $this->key . "' ";
            }
        }

        $this->dsn = rtrim($this->dsn);
    }

    // --------------------------------------------------------------------

    /**
     * Database connection
     *
     * @param    bool $persistent
     * @return    resource
     */
    public function db_connect($persistent = FALSE)
    {
        $this->conn_id = ($persistent === TRUE)
            ? pg_pconnect($this->dsn)
            : pg_connect($this->dsn);

        if ($this->conn_id !== FALSE) {
            if ($persistent === TRUE
                && pg_connection_status($this->conn_id) === PGSQL_CONNECTION_BAD
                && pg_ping($this->conn_id) === FALSE
            ) {
                return FALSE;
            }

            empty($this->schema) OR $this->simple_query('SET search_path TO ' . $this->schema . ',public');
        }

        return $this->conn_id;
    }

    // --------------------------------------------------------------------

    /**
     * Reconnect
     *
     * Keep / reestablish the db connection if no queries have been
     * sent for a length of time exceeding the server's idle timeout
     *
     * @return    void
     */
    public function reconnect()
    {
        if (pg_ping($this->conn_id) === FALSE) {
            $this->conn_id = FALSE;
        }
    }

    // --------------------------------------------------------------------

    /**
     * Set client character set
     *
     * @param    string $charset
     * @return    bool
     */
    protected function _db_set_charset($charset)
    {
        return (pg_set_client_encoding($this->conn_id, $charset) === 0);
    }

    // --------------------------------------------------------------------

    /**
     * Database version number
     *
     * @return    string
     */
    public function version()
    {
        if (isset($this->data_cache['version'])) {
            return $this->data_cache['version'];
        }

        if (!$this->conn_id OR ($pg_version = pg_version($this->conn_id)) === FALSE) {
            return FALSE;
        }

        /* If PHP was compiled with PostgreSQL lib versions earlier
         * than 7.4, pg_version() won't return the server version
         * and so we'll have to fall back to running a query in
         * order to get it.
         */
        return isset($pg_version['server'])
            ? $this->data_cache['version'] = $pg_version['server']
            : parent::version();
    }

    // --------------------------------------------------------------------

    /**
     * Execute the query
     *
     * @param    string $sql an SQL query
     * @return    resource
     */
    protected function _execute($sql)
    {
        return pg_query($this->conn_id, $sql);
    }

    // --------------------------------------------------------------------

    /**
     * Begin Transaction
     *
     * @return    bool
     */
    protected function _trans_begin()
    {
        return (bool)pg_query($this->conn_id, 'BEGIN');
    }

    // --------------------------------------------------------------------

    /**
     * Commit Transaction
     *
     * @return    bool
     */
    protected function _trans_commit()
    {
        return (bool)pg_query($this->conn_id, 'COMMIT');
    }

    // --------------------------------------------------------------------

    /**
     * Rollback Transaction
     *
     * @return    bool
     */
    protected function _trans_rollback()
    {
        return (bool)pg_query($this->conn_id, 'ROLLBACK');
    }

    // --------------------------------------------------------------------

    /**
     * Determines if a query is a "write" type.
     *
     * @param    string    An SQL query string
     * @return    bool
     */
    public function is_write_type($sql)
    {
        if (preg_match('#^(INSERT|UPDATE).*RETURNING\s.+(\,\s?.+)*$#is', $sql)) {
            return FALSE;
        }

        return parent::is_write_type($sql);
    }

    // --------------------------------------------------------------------

    /**
     * Platform-dependant string escape
     *
     * @param    string
     * @return    string
     */
    protected function _escape_str($str)
    {
        return pg_escape_string($this->conn_id, $str);
    }

    // --------------------------------------------------------------------

    /**
     * "Smart" Escape String
     *
     * Escapes data based on type
     *
     * @param    string $str
     * @return    mixed
     */
    public function escape($str)
    {
        if (is_php('5.4.4') && (is_string($str) OR (is_object($str) && method_exists($str, '__toString')))) {
            return pg_escape_literal($this->conn_id, $str);
        } elseif (is_bool($str)) {
            return ($str) ? 'TRUE' : 'FALSE';
        }

        return parent::escape($str);
    }

    // --------------------------------------------------------------------

    /**
     * Affected Rows
     *
     * @return    int
     */
    public function affected_rows()
    {
        return pg_affected_rows($this->result_id);
    }

    // --------------------------------------------------------------------

    /**
     * Insert ID
     *
     * @return    string
     */
    public function insert_id()
    {
        $v = pg_version($this->conn_id);
        $v = isset($v['server']) ? $v['server'] : 0; // 'server' key is only available since PosgreSQL 7.4

        $table = (func_num_args() > 0) ? func_get_arg(0) : NULL;
        $column = (func_num_args() > 1) ? func_get_arg(1) : NULL;

        if ($table === NULL && $v >= '8.1') {
            $sql = 'SELECT LASTVAL() AS ins_id';
        } elseif ($table !== NULL) {
            if ($column !== NULL && $v >= '8.0') {
                $sql = 'SELECT pg_get_serial_sequence(\'' . $table . "', '" . $column . "') AS seq";
                $query = $this->query($sql);
                $query = $query->row();
                $seq = $query->seq;
            } else {
                // seq_name passed in table parameter
                $seq = $table;
            }

            $sql = 'SELECT CURRVAL(\'' . $seq . "') AS ins_id";
        } else {
            return pg_last_oid($this->result_id);
        }

        $query = $this->query($sql);
        $query = $query->row();
        return (int)$query->ins_id;
    }

    // --------------------------------------------------------------------

    /**
     * Show table query
     *
     * Generates a platform-specific query string so that the table names can be fetched
     *
     * @param    bool $prefix_limit
     * @return    string
     */
    protected function _list_tables($prefix_limit = FALSE)
    {
        $sql = 'SELECT "table_name" FROM "information_schema"."tables" WHERE "table_schema" = \'' . $this->schema . "'";

        if ($prefix_limit !== FALSE && $this->dbprefix !== '') {
            return $sql . ' AND "table_name" LIKE \''
            . $this->escape_like_str($this->dbprefix) . "%' "
            . sprintf($this->_like_escape_str, $this->_like_escape_chr);
        }

        return $sql;
    }

    // --------------------------------------------------------------------

    /**
     * List column query
     *
     * Generates a platform-specific query string so that the column names can be fetched
     *
     * @param    string $table
     * @return    string
     */
    protected function _list_columns($table = '')
    {
        return 'SELECT "column_name"
			FROM "information_schema"."columns"
			WHERE LOWER("table_name") = ' . $this->escape(strtolower($table));
    }

    // --------------------------------------------------------------------

    /**
     * Returns an object with field data
     *
     * @param    string $table
     * @return    array
     */
    public function field_data($table)
    {
        $sql = 'SELECT "column_name", "data_type", "character_maximum_length", "numeric_precision", "column_default"
			FROM "information_schema"."columns"
			WHERE LOWER("table_name") = ' . $this->escape(strtolower($table));

        if (($query = $this->query($sql)) === FALSE) {
            return FALSE;
        }
        $query = $query->result_object();

        $retval = array();
        for ($i = 0, $c = count($query); $i < $c; $i++) {
            $retval[$i] = new stdClass();
            $retval[$i]->name = $query[$i]->column_name;
            $retval[$i]->type = $query[$i]->data_type;
            $retval[$i]->max_length = ($query[$i]->character_maximum_length > 0) ? $query[$i]->character_maximum_length : $query[$i]->numeric_precision;
            $retval[$i]->default = $query[$i]->column_default;
        }

        return $retval;
    }

    // --------------------------------------------------------------------

    /**
     * Error
     *
     * Returns an array containing code and message of the last
     * database error that has occured.
     *
     * @return    array
     */
    public function error()
    {
        return array('code' => '', 'message' => pg_last_error($this->conn_id));
    }

    // --------------------------------------------------------------------

    /**
     * ORDER BY
     *
     * @param    string $orderby
     * @param    string $direction ASC, DESC or RANDOM
     * @param    bool $escape
     * @return    object
     */
    public function order_by($orderby, $direction = '', $escape = NULL)
    {
        $direction = strtoupper(trim($direction));
        if ($direction === 'RANDOM') {
            if (!is_float($orderby) && ctype_digit((string)$orderby)) {
                $orderby = ($orderby > 1)
                    ? (float)'0.' . $orderby
                    : (float)$orderby;
            }

            if (is_float($orderby)) {
                $this->simple_query('SET SEED ' . $orderby);
            }

            $orderby = $this->_random_keyword[0];
            $direction = '';
            $escape = FALSE;
        }

        return parent::order_by($orderby, $direction, $escape);
    }

    // --------------------------------------------------------------------

    /**
     * Update statement
     *
     * Generates a platform-specific update string from the supplied data
     *
     * @param    string $table
     * @param    array $values
     * @return    string
     */
    protected function _update($table, $values)
    {
        $this->qb_limit = FALSE;
        $this->qb_orderby = array();
        return parent::_update($table, $values);
    }

    // --------------------------------------------------------------------

    /**
     * Update_Batch statement
     *
     * Generates a platform-specific batch update string from the supplied data
     *
     * @param    string $table Table name
     * @param    array $values Update data
     * @param    string $index WHERE key
     * @return    string
     */
    protected function _update_batch($table, $values, $index)
    {
        $ids = array();
        foreach ($values as $key => $val) {
            $ids[] = $val[$index];

            foreach (array_keys($val) as $field) {
                if ($field !== $index) {
                    $final[$field][] = 'WHEN ' . $val[$index] . ' THEN ' . $val[$field];
                }
            }
        }

        $cases = '';
        foreach ($final as $k => $v) {
            $cases .= $k . ' = (CASE ' . $index . "\n"
                . implode("\n", $v) . "\n"
                . 'ELSE ' . $k . ' END), ';
        }

        $this->where($index . ' IN(' . implode(',', $ids) . ')', NULL, FALSE);

        return 'UPDATE ' . $table . ' SET ' . substr($cases, 0, -2) . $this->_compile_wh('qb_where');
    }

    // --------------------------------------------------------------------

    /**
     * Delete statement
     *
     * Generates a platform-specific delete string from the supplied data
     *
     * @param    string $table
     * @return    string
     */
    protected function _delete($table)
    {
        $this->qb_limit = FALSE;
        return parent::_delete($table);
    }

    // --------------------------------------------------------------------

    /**
     * LIMIT
     *
     * Generates a platform-specific LIMIT clause
     *
     * @param    string $sql SQL Query
     * @return    string
     */
    protected function _limit($sql)
    {
        return $sql . ' LIMIT ' . $this->qb_limit . ($this->qb_offset ? ' OFFSET ' . $this->qb_offset : '');
    }

    // --------------------------------------------------------------------

    /**
     * Close DB Connection
     *
     * @return    void
     */
    protected function _close()
    {
        pg_close($this->conn_id);
    }

}
